STATISTICAL CHARACTERISTIC OF ATMOSPHERIC BLOCKING IN THE EURASIA HIGH-MID LATITUDES BASED ON RECENT 30-YEAR SUMMERS

According to synoptic definition of blocking, a objective method is used to statistic atmospheric blocking in Eurasia high-mid latitudes based on 32-year summers by means of 1970-2001 NCEP analysis data. The results show that there are 392 blocking activities during period of past 32 summers. Blocking activity occur frequently in zone of 45-70°N, concentrate on five regions mainly, especially in Ural and the east part of Baikal. Most of them are less than 10 days. The feature of the blocking activity intra-seasonal variations is clear. Ural and Okhotsk are preferred areas for the blocking, occurring in form of double-blocking in Jun. the blocking activities increase in Baikal and Europe, particularly in the east part of Baikal, the activities decrease synchronously in Ural and they appear more frequently in North to 60°N in the Okhotsk area. Therefore, Mid-blocking pattern is more important in Jul. The change is more obvious, the mid-blocking that occur in Baikal is most remarkable in Aug.